Workshift Changes in Hydration Status During Wildfire Suppression

Objective: Document wildland firefighters (WLFFs) hydration status during a singular workshift (13.7 +/- 1.4 hours). Methods: WLFF researchers documented real-time WLFF (n = 71) urine metrics and fluid consumption. Body weight and blood samples (n = 25) were also collected. Two-tailed dependent t tests determined statistical significance (P < 0.05). Results: Body weight significantly decreased (-0.3 +/- 1.1%, P > 0.05). Fluid consumption totaled 6.2 +/- 2.3 L including food and 5.0 +/- 2.1 L without food. Morning versus afternoon urine frequency (2.6 +/- 1.3, 3.1 +/- 1.9 voids), urine volume (1.2 +/- 0.7, 1.3 +/- 0.8 L), urine volume per void (440 +/- 157, 397 +/- 142 mL), and urine specific gravity (1.010 +/- 0.007, 1.010 +/- 0.007) were not significantly different (P > 0.05). Pre- to post-workshift serum chloride (103.2 +/- 1.9, 101.4 +/- 1.7 mM) and blood glucose (5.2 +/- 0.4, 4.5 +/- 0.7 mM) significantly decreased (P < 0.05), while serum sodium (141.5 +/- 2.4, 140.8 +/- 2.0 mM) and serum potassium (4.3 +/- 0.3, 4.2 +/- 0.3 mM) remained stable (P > 0.05). Conclusions: WLFFs can ingest fluid and food amounts that maintain workshift euhydration and electrolyte status.